1. Field of the Invention
The invention pertains to a suspension strut unit including a cylinder and a height-adjustable spring collar having a sleeve section by which it is connected to the cylinder.
2. Description of the Related Art
A suspension strut unit with a detachable spring collar is known from DE 85 10 058 U1, where the spring collar is supported in a retaining ring. The retaining ring for its own part can be attached independently of the spring collar to the cylinder of the suspension strut unit, together with which it can be coated as a separate structural component. The height of the spring collar is determined by the retaining ring and cannot be changed.
DE 198 51 019 C1 discloses a suspension strut unit with a cylinder, which carries a retaining ring for a spring collar; the height of the collar can be adjusted as desired and then held permanently in position there. The retaining ring is provided with at least one groove, into which at least one circumferential area of a sleeve section of the spring collar can be radially deformed. The degree to which the sleeve section overlaps the groove determines the maximum extent to which the height of the spring collar can be adjusted.
A spring assembly for motor vehicles is also known from DE 197 44 757 A1. In this case, the height of the spring collar can be actively changed by the use of a hydraulic medium. A spring assembly of this type is intended especially for vehicles of the luxury class, in which it must be anticipated that a system for automatically controlling the level of the vehicle body will require the relatively frequent adjustment of the height of the spring collar.